This invention relates to the removal of objects from tubular body passages, and it relates in particular to a new and improved method and device for removing such objects.
There are numerous medical situations in which an object becomes positioned in a tubular body passage under conditions which can cause damage to the person. The most significant of these conditions involves the formation of blood clots in the arterial passages. Other conditions involving such blockages include stones located in the urinary passages and foreign objects blocking the esophagus. Although the present invention is applicable for removing any of these or other non-liquid objects located within a tubular body passage, the more significant situation relates to blood clots. Accordingly, while the present invention is adaptable for removing objects in any of the body's tubular passages, it will be described in particular with reference to removal of blood clots in the arterial passageways.
Heretofore it is believed that two approaches have been developed for the removal of blood clots (for example, emboli, thrombi, etc.) from arterial or venous systems. One of these concepts, which has been used successfully only for extracting pulmory emboli involves the use of a catheter having a suction cup at the end thereof.
Another approach which has more universal application is a catheter having a balloon at the distal end thereof which inflates outwardly to use the mechanism of fluid displacement for removing the clots. Such an arrangement is known as the Fogarty Arterial Embolectomy Catheter, hereinafter referred to as the balloon catheter. Such an arrangement is shown generally in the Fogarty U.S. Pat. No. 4,338,942. However, considerable disadvantages have been found to exist with respect to the balloon catheter. One problem is that the catheter is forced directly through the clot which pushes a portion thereof further distally in the arterial tree. On occasion, these portions are unretrievable. A second problem is that when the balloon is inflated and expands outwardly, a portion of the clot is forced outwardly to press against the interior wall of the artery. When the balloon is withdrawn, the portion which was pressed against the interior wall creates a "snow plow" effect which means in effect that a small portion of the clot is deposited at the smaller branches of the artery which it passes, blocking them off. A third problem associated with the prior balloon catheter, which is perhaps the most serious problem, is that if the balloon should be over inflated, it can cause severe and irreparable damage to the interior wall of the artery. In fact, if the balloon is over inflated to the point of rupturing the artery (which does in fact occur) not only is the interior wall damaged, but a portion of the balloon remains inside of the artery, blocking blood flow and quite possibly leading to the loss of a limb.
Hence, there exists a need for improvements in the field of removing objects from tubular body passages, especially arterial passageways, wherein the disadvantages of the prior art are overcome.